Heating means for sheet-glass apparatus



Nov. 181930. J. L. BRAKE HEATING MEANS FOR SJHEET GLASS APPARATUS Filed Nov. 17. 1926 .Patented Navi. 1s, 1930 AUmTigzn STATES PATENT OFFICE JOIHIN, L. BRAKE, OF '.lOLlLDO, OHIO, ASSIGNOR TO LIBBEY-OWENSfFORD GLASS COM- 1 PANY, 0F TOLEDO, OHO, A CORPORATION OF OHIO HEATING MEANS non SHEET-GLASS ArrARATUs 'Application led November 17, 1926. -vSerial No. 148,789.

This invention relatesto sheet' glass appa-i lwhile still in a's'emi-plastic condition, al-

though substantially setin its nal sheet form, is bent into a horizontal plane about a rotatable bending member and carried olf through a suitable drawing mechanism and intoan annealing leer. Heretofore, a certain portion ofthe glass contained within v the draw pot would after a time, become cooled and subsequently de'vitritied to form so-called dog metal. This dog Jmetal is detrimental to the production of a good sheet of glass and consequently mustbe removed from time to time. This can only be accomplished, however, by shutting down the machine and boiling or cleaning out the draw pot, which of course, consumes considerable timev and labor and reduces the output of the machine.

It is, therefore, the primary object of th1s invention to provide, insheet glass apparatus, improved means/for heat-ing the receptacle or draw pot and the molten glass contained therein whereby to reduce to a minimumA the formation'ofAso-,called dog metal.

Another important object of the invention I is to'provide, in sheet glass apparatus, means for maintaining the mass of molten lglass within the receptacle at a relatively'constantand uniform temperature to aid in the drawing of agood sheet of lass. g.

A further object o the lnventlon 1s to provide, in sheet glass apparatus, means. for heating the receptacle and molten glass contained therein, and means forv automatically reducing the heating` effect ofthe heating means when the molten glass reaches a predetermined temperature.

A further object of the invention is to provide, in sheet glass apparatus, means for preventing the temperature of the molten glass within the receptacle from falling below a predetermined point.

of molten glass` A still further objectiofthe invention is Y the provision of means for heating the molten glass within the receptacle, together with additional means for heating the glass and forautomatically lessening the heating effeet of the first heating means when the temperature 'of said glass reaches a predetermined point. Y A

Other objects and advantagesof the invention will become more apparent during the course of the following description when taken in connection withthe accompanying.

drawings.

In the drawings forming apart of this.

application and wherein like numerals are employed to designate like parts throughout the same,

ig. 1 is a vertical longitudinal section through improved sheet glass apparatus constructed in accordance with the presentinvention.

sFig. 2 is a vertical section taken on linel 2-2 of Fig. 1.

a receptacle or draw pot which maybe formed from a suitable refractory material In the drawings, the numeral 5 designates and which is continuously replenished with a source of molten glass 6 from any form of tank 7. The receptacle 5 is supported upon stools 8, and is also heated from beneath by burners which are not shown. A sheet ofglass 9 is drawn upwardly from the source of molten glass 6 and at a substantial distance therefrom is deflected'into a horizontal Y plane over a bending member 10, after which the saidl sheet is passed over an idle roll p 11, through a drawing mechanism 12, -into an annealing leer where it is gradually reduced to'room temperature as is well known inthe f oo Arranged above the receptacle 5 are cover or lip tiles 13 which tend to force any heat,

art.

position downwardly the molten glass 6.

currents present at that toward the surface of Cooling members 14 are arranged at opposite sides of the sheet and closely adjacent the surface of the molten glass 6 to said'sheet and to also absorb su cientheat fromthe glass passing thereunder topermit the drawing of a good sheet of glass. To

rotect the maintain the sheet to width, knurled rollersl 15, or similar means, are arranged to engage opposite sides of the sheet at both edges thereof. l

In accordance with the present invention, a plurality of electrodes 16 are arranged at opposite sides of the receptacle 5, said electrodes depending downwardly into the molten glass 6 as shown in Fig. 2 and being carried by brackets 17. Any suitable number of these electrodes may be used and they may be positioned atA any desired distance apart. -Each pair of oppositely disposed electrodes are adapted to be connected by means of an electrical heat resistance element consisting of one or any preferred number of wires 18, said Wires being arranged Within. the side walls and bottom wall of the'receptacle 5. Thus, the electrodes and resistance elements are, connected in parallel.

It is well known that glass at high temperatures, and especially when in a molten condition, becomes a relatively good conductor of electricity and this property of becoming a fairly good electrical conductor when molten, makes it possible to heat glass electrically by the passage `of a suiiciently heavy current therethrough. However, when the temperature of glass falls to a certain point, it loses its powers of conductivity and becomes an insulator. Y

In operation, when the glass is at such a temperature as to insulate the electrodes 16 from each other, all of the current will pass through the resistance elements 18 which will then function to heat up the glass. When the glass reaches such a temperature as to become a conductor, however, a part of the current will then pass through the molten glass and a part through the resistance elements. Broadly stated, the current will divide between the two paths of the parallel circuit, in inverse. ratio to the resistances of the two paths. In other words, when the resistance elements 18 offer less resistance than the molten glass, a greater portion of the current will pass therethrough but, on the other hand, when the glass is heated to a temperature where it oers less resistance to the electric current .than the resistance wires 18, a greater' portion of the electric current will pass through the molten glass between the electrodes 16. For example, the heat resistance elements 18, arranged within the walls of receptacle 5, are adapted to have less electrical resistance than the moltenv glass at a temperature ofv1600 Fahrenheit but greater resistance than the glass at 1800o Fahrenheit. Consequently, when the temperature of the molten glass is at approximately 1600 Fahrenheit or less (but sufliciently vhigh to still render it a conductor) a greater portion ofthe electric current will pass through the elements 18 to heat up the glass but when the temperature of the molten glass reaches through the molten glass will act to heat the sameand maintain it at'a relatively predetermined constant and uniform temperature.

The wires 18 not only serve to heat the glass up to a desired temperature initially, but also act as a safety means and should the glass, for one reason or another, become cooled and the temperature thereof drop to 1600o Fahrenheit, a greater portion of the current will automatically pass through the said wires18so that they will again function to heat the molten glass up to a point where a greater portion of the electrical current will be caused to pass through the said glass. Y

' By the provision of the present improved heating means, the molten glass 6 will always be maintained at a relatively constant temperature, and the maintaining of the glass at such "a relatively constant temperaturewill aid'inthe drawing of a good sheet of glass. Moreover, with such an arrangement, the formation of dog metal within the receptacle will be reduced to a minimum inasmuch as the molten glass contained therein will not bel permitted to cool to .such a dey' gree as will allow the glass to become devitrii'ied. i Y

It is to be understood that the form of the invention herewith shown and described is to be taken as the preferred embodiment of the same, and that various changes in the shape, size and arrangement .of parts may be resorted to without departing from the spirit ofthe invention or the scope of the `sub joined claims.

Claims:

1. In glass apparatus, a receptacle adapted to contain a mass of molten glass, an electrical heat resistance element for heating said glass, and a plurality of electrodes acting to automatically lessen the heating effect of said heat resistance element when the glass reaches a predetermined temperature, said electrodes then functioning to effect a heating of the glass whereby to maintain it at such predetermined temperature;

2. In' glass apparatus, a receptacle adapted to contain a mass of molten glass, an electrical heat resistance element for heating said glass, and a plurality ofelectrodes depending within the glass for lessening the heating effect of said heat resistance element when the glass reaches a predetermined temperature, said electrodes being then auto- 'matically connected to eect a heating of the glass whereby to maintainv Ait at suchpredetermined temperature.

3. In glass apparatus, ed to contain a mass of molten glass, av plurality of `electrical heat resistance elements arranged within the Walls of said receptacle for heating the molten 'glass contained there- 'for heating said glass, and additional'meansfr heating the glass and for automatically reducing thefheating eii'ect of the first heating means whenthe glass reaches a predetermined temperature.

5.- In glass apparatus, a receptacle adaptedto contain a mass of molten glass, electrically operated means for heating-saidglass, andadditional electrically operated means for heating the glass' andfor auto- -matically reducing the heating effect of the` first heatingmeans when the molten-glass reaches a predetermined temperature.

6. In glass apparatus, a receptacle adapted to contain a massof molten glass, an, electrical heat resistance element for heating said glass, and a plurality of electrodes for also heating the sistance element when the molten glass reaches a predetermined temperature. 7. In glass apparatus, a receptacle containing a mass of molten glass, two sets of heating means associated with said receptacle, said sets of heating means being inter-related in a manner that one set is rst used for heating the glass in the. receptacle Aand the .other set then used to maintain the glass at the desired temperature, the temperature of the glass effecting the change from one set of heating means'to the other.

8. In glassapparatus, a receptacle containing a. mass of molten glass, two sets of heating.

means associated with said receptacle, said sets of heating means being inter-related in a manner that ,one set is irst used `for heat-l ing the glass in the receptacle and the other set then used to maintain the glass at the de sired temperature, vthe `temperature of lthe 1 glass eecting'the change from one set of heating means to the other, the change from one set of heating means to the other being automatic When the glass reaches a predeterminedtemperature. v

9. In glass apparatus, a' receptacle containing a mass of molten glass, two sets of heatin means associated with said receptacle, said sets of heating meansrbeing inter-related in a manner that one set is irst used a receptacle adapt- A heating means associated with .tacle, saidsets of heating means glass and for automatically, reducing the heating effect of the said 'retempera'ture',` 'eecting the change from vbue-set for heating the glass in the receptacle and the other set then used to maintain the glass at the desired temperature, the temperature vo the glass effectingv the change from one set ofheating means tothe other, one set of heatingmeans having a portion immersed in said molten glass.

v 10. In glass apparatus, areceptacle containinga mass of molten glass, two sets of heating means associated with said receptacle,

saidsets 'of heatingmeans-being inter-'related 'in a manner that one setlis first used for heating the glass in lthe receptacle andthe other set then used to maintain the glass at the desired temperature, the temperature. of' the glass eecting the change'from one set vof heating means to the other,

one setof heatingmeans having a portion .immersed in said molten glass, the c ange from oneset 'of heating means to theother being automatic when the glass reaches apredetermined temperature;

11. In glass apparatus, a receptacle con-,

taining a mass of molten glass, two sets of said recepbeing interrelated in a manner that one set is first used for heating the glass lin the receptacle and' theother set then used to maintain the'glass at the desi-red temperature, the temperature of the" glass lelecting" the change vfrom one set of heating means to the other, one set of heating means lhaving a` portion immersed in said molten `gl`ass ,and the other set of heating means being'arranged in the walls of said receptacle.

12. In glass apparatus, a receptacleconheating means associated with saidv receptacle, said sets of heating meansheing inter-A relatedin a mannerthat one set is rst used for heating the glass inthe receptacle and the other set then used to maintain the glass at the desired temperature, the temperature of the glasseffecting the change from onesetl of heating means to the other,.one set of heat- 'taining amass o f molten glass, two sets of ing means having a portion immersed in said moltenY glass, and the other setof heating means being arranged'in the walls-of said receptacle, the change from one set of heating mea-ns to the other being automatic when the" glass reaches a. predetermined temperature.

13. In glass, apparatus, a receptacle containingA a mass of molten glass, two sets of electrical heating'means associated with said receptacle and arranged in parallel, said sets of 'heating means being inter-related in-a manner that one set is first used for heating the glass in the receptacle and the other set then used to maintain the glass at the desired the'temperature of the glass means to the other.

of heating.

14, In glass apparatus, a receptacle conf taining a mass of moltenl glass, two sets of I electrical heating means associated with the receptacle, one set of electrical hesating means being embedded in the Walls of the receptacle, the other set of electrical heating means having portions immersed in the lmass of molten glass, the tWo sets of heating means being arranged in parallel in a manner that one s'et is first used for heating the glass in the receptacle and the other set then used to maintain the glass at the desired temperature, the temperature of the glass effecting the change from one set of heating means to the other.

15.A In glass apparatus, a receptacle containing a mass ofmolten glass, two sets of electrical heating means associated with the receptacle, one set of electrical heating means being embedded in the Walls of the receptacle, the other set of electrical heating means having portions immersed in the mass of molten glass, Jthe two sets of heating means being connected in parallel in a manner that one set is first used for heating the glass in the receptacle and the other set then used to maintain the glass atthe desired temperature, the temperature of the glass effecting the change from one set of heating means to the other, the change from one set of heating means to the other being automatic when the glass attains a predetermined temperature.

16. In glass apparatus, a receptacle adapted to contain a mass of molten glass, electrical means for heating the glass, and elec- 5 T when the temperature ofthe glass rises to a predetermined point.

Si ned at Toledo, in the county of Lucas and tate of Ohio, this 13th day of November, 1926.

'- JOHN L. DRAKE.

trical means for automatically reducing the A l heating effect of said heating means when v the glass reaches a predetermined temperature, said electrical reducing means then acting as a heating means to maintain the glass at such predetermined temperature.

17. In glass apparatus, a receptacle adapted t0 contain a mass of molten glass, electrical heating means for heating the glass, and additional electrical heating'means acting to automatically lessen the heating effect of the first mentioned heatingkmeans when the glass reaches a predetermined temperature, said irst and second named heating means being connected in parallel, and a portion of the second named heating means be- 'ing disposed within the molten glass.

18. In glass apparatus, a Y receptacle adapted to contain a mass of molten glass, -a plurality of electrical resistance elements arranged out of contact with the glass but provided to heat the same, and a plurality of electrodes immersed within the molten glass and also adapted to heat thejsame, said resisance elements and electrodes'being connected in parallel, a greater portion of the electric current passing through the resistance elements when the temperature of the glass falls below a predetermined point and a greater portion of the current passing through the glass between the electrodes 

